.current {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: #fff;
  border: 1px solid #ccc;
}
.animation {
  animation: changeColor 1s ;
  background: yellowgreen;
}
@keyframes changeColor {
  0% {
    background: #c00;
  }
  50% {
    background: orange;
  }
  100% {
    background: yellowgreen;
  }
}
